Process for the electrolysis of alkali chlorids.



v J. BILLITZER. PROCESS FOR THE ELEGTROILYSIS or ALKALI ,GHLOEIDS.

APPLICATION FILED 1131122, 1907. i

Patented July 20, 1909.

To all whom it may cone UN TED STATES PATENT oFrIoE.

JEAN BI LITZER, or VIENNA, AUSTRIA-HUNGARY.

PROCESS FOR THE ELECTROLYSIS F ALKALI CHLORIDS.

. h Be it known that. 1I,=, JnAN BlLLlTZER, chemist, a sub ect of the Emperor of Austria-Hungary, residing at RGISIIQLSUHSSQ 21,

Vienna, III, Austria-Hungary, have invent ed certain new and useful Improvements in Processes for the Electrolysis of Alkali .(lhlorids, of which tl'le'following is a full,

clear, and exact description. I

It is well known that d iliiculty 1s encountered in obtaining chlorin and fairly concen- 1 trated soda lye from chlor1d of sodium solu-' tions, by means of the electric current and cheap and snnple apparatus of good current e'fiiciency. The types of mercury apparatus,

- though operating satisfactorily, are very expensive, complicated and require careful attention. I v

The bell apparatus while giving a comparatively good yield, requires a high tension during the, electrolysis and does not yield concentrated lyes.

In order to obtaina good yield of concentrated lye applicant has devised a new process. This process though principally designed for the chlorid of sodium electrolysis may be also employed without any difficulty in all cases in which through the action of the electric current upon a solution a gaseous:

and a liquid product is formed.

The idea'involved in this process is shortly .as follows: In a suitably arranged apparatus,

the anodes are disposed above the substantially horizontal cathodes with a diaphragm also substantially horizontally between them. Between the anodes and this diaphragm a formation of layers is produced by means of the electrolysis, which renders the solution weaker. This Will diminish the density of the anode solution, while the portion of the solution next .to the cathode,and' -im1nediately above the diaphragm W.1ll increase its specific weight and thus gravitate as alayer next to the diaphragm. Since layers. of liquids at rest cannot be kept forany length offtime from diffusing into each othel'f-the two solutions thus produced are so arated by sup+ plying fresh-' salt solution rom above and by compelling the lower heavier layer to flow through a slot, disposed near the diaphragm and extending over the whole width of the latter, and by arranging a dam behind this slot. By these means the heavier layerwill be constantly removed as it is Specificationof Letters Patent. iiipplleation filed January 22,1907. Serial No. 353,473.

Patented .Ti11y20, 1909'.

formed. In order to obtain stationary condi'tions the supply of freshsalt solution and the current intensity have to be chosen so matter of a divisional application Serial No.

This dia- 8,981, filed June 17th, 1908. phragm has, aside from its many other ad vantages, the particular features of having an accurately regulatable permeability and of adapting itself well to the form of the cathode, so' that the separation, aside from being produced by the formation of layers, is further aided by the inner hydrostatic pressure. Furthermore, through the rewet ting of the cathode by means of the solution running off, the contact is kept permanent and the running off of the soda lye insured.

According to applicants method above described has the separation into layers of small quantities of liquid been. rendered possible, .and this only by having the separating layerthin by causing same to renew itself automatically during the process of electrolysis and byforcing it to form a dis tinct' separating layer. Only by this arrangement it has been made possible to completely separate anode and cathode products, obtaining at the same time coniparativelyconcentrated solutions 'of soda lye, that per cen solutions of from ten to twenty In order to make clear the invention, the process will be described in detail in the ,I

following with the aid of the accompany ing drawings'which show diagrammatically an apparatus used for this process.

In these drawings Figure 1 1s 'a part of a longitudinal section ofthe apparatus; I

2 is a transverse section of 'same; Fig. 3 1s a' longitudinal sect-ionof a modification of the apparatus.

The apparatus shown in Figs. land 2 comprises a 'bell which isclosed at its shown, tor-instance, in 'l-at 22,- or re}. 15.

, used.

lower end by .means of a diaphragm 1,.

resting upon a wire. net 3 of iron, nickel or other suitable material, wh ch -serves as the negative electrode-J The entire hell is 'suitably supportedfand disp osedwithin a, trough 10. -Within bell 1lis arranged-anode 8,025

platinum, carbon or other su table material in parallel to and'atasmall distance from a the cathodefnet g-i In manufacturing the" apparatus various materials may be employed; Plates of glass,

wire-glajss or- "pottery may be used, which are embeddedinscement or in 'aspha1t ,.-as

inforeed concrete" or stone: plates 7 may 7 be In order obtaiu-a complete separation "ofthe; electrolytic"; products 1 (soda lye and e ilbr n) h r es is? a ed n -i the following manner: ""lhe-bell, ll'i'is' supplied with lthe 'electrolyti'af g-to" acertain height,

troughs-1O being empty at the beginning of e Pm s-.. T a tem being p r able for liquidsgwill; ja w t l1e'- salt solution to percoldte throngh jtoathe cathode where soda lye isjforinedr i The' ;disoharge opening 13 forthelye' is disposedi'so that-the liquid passing into trough will-attain a, suitable height to just wet- "t'hecathode 'net.'

In order to facilitate thejesjcape offlthe;hy-

, drogen bubbles produced-=1 0.1L the cathode during the electrolysis; "the Icath'odeimay be a suitably shaped for finstancefby arranging arrangement however is 'jonlyfypo'ssibl 1 20 wouldbe suiiicient to; cause the hydro gen to wander}. toward the higher porti'on,

offthenet. v A satisfactory" operation-of. th

' .using a suitable kindi of diaphragm.

' suited for this purpose', Pulverized" essential. to use diaphragms, the. perm ity of which for liquids is accuratelyg regil latable'jwithoutoffering great 'elecvtrieal re-j sistance, and which adapt themselyes-well to.- the form -of cathode, which are not pliable-such; asfcarbQ lBldum cement, sheet asbestos'and the like "ar p'hragms are 'notv suited either,- si'nce "they;

are not plastie, aiid-arefnot e'rinanent Applicant; has; succeede new diaphragm bycover-in the net cathode;

3 with ordinary commercia asbestos cloth I (Fig'. 1) and putting-on same apulverized diaphragm 2 ofaparti'cular kind. The pulverized J diaphragms heretofore known are not suited for inclined surfaces, 'owin to the powder. soon shifting down the inc ine. Besides .thesediaphragms have the disadvantage of cementing and thus soon becoming impermeable; for. this latter reason they l the diaphragm. In order to further facili- 130 in designing a cannot be used for this purpose even in connection with fixed ribs, which prevent the sliding ofjthe powder. Both of said disadvantages havebeen overcome by applicant by using a diaphragm body consistmg'of a mixture of insoluble powders, such as sul fate of barium, clay or the like, and "'aaisbestoswool, which mixture is formed in sodium "chlorid solutions into a lastie jbut-T's'till tough and resistive mass. able powders with asbestos wool can be made very quickly and veryeasily ixtures of suit- While for in-:

stance sulfatefof barium a n requires-several hours to deposit, a suspended mixture of pulverized sulfate of barlumand asbestosjwooldeposits. in a twenty- (20%) per cent.

sodium chlorid solution in a few minutes.

Thiskdeposit beingat. first tou h, maybe easi1y.-'dried,.wherehy it maybe ormed into any shape," which it retains during "its further use foralong'tinie even in li uids.

These .diaphragms are extreme y strong 'and'may' be used for months and years and furthermore they. can be exchanged or re- ,newed-very quickly and easily, contrary to ordinary powder diaphragms. It is only necessary to renew the asbestos-wool powder layerorato exchange the whole diaphragm by lifting out the asbestos cloth with. the

layer. This operation requires onlya few minutes. "These dia hragms dry sand harden in the air comp et'elyafter some time,

, but L egain their pliabilityand' permeability" .-when'placed for a short time-in wa'teror in "'a 'solutionofiany suitablekind; B varying 111 a the roportion" of asbestos woo nda sOgwithfroinfi to lOvgrams asestos-wool for obtaining ,still more coni'g lfiiims of asbestoswool. .v g F D ring the-electrolys s in the apparatus "describe 10 while the-chlorin ions wander to the anode where they are discharged and escape as gaseousychlorim Fresh salt solution is supplied through .feedingpipe 12 (.Fig. 2)

ight 1t b;' thirteen per cent-1011a diaphragm; 1' 99 above soda lye is formed introughte of arlumjor clay powder, sils'lwell-gns by varyingthe thickness of the layer, the. permeability of the diaphragm be -regulated at W111; i

+1 es, two' hundred and seventy-live which runs into thesolutlon close to the diaphragxm 'Therefore the upper portion of the salt solution will be weakened in salt dur- ;1n the electrolysis while the lower portion w i 1 increase its density so that owing to the different dens ties of. the two portions, .a distinct layer is formed immediately above tate the formation of thelayer a chamber or' pocket 9 (Fig. 2) of im aermeable material may be provided in the ell, which is sup; plied with cooking salt, and which communi cates near the bottom with the electrolysis chan'iber, so that the layer resting directly upon the diaphgram is constantly saturate with cooking salt and therefore its specific .weight rendered sti greater. "This latter 10 precaution is particurarly advisable when the fresh solution is supplied very slowly in order to obtain very concentrated lyes." In this case the solution would grow too weak in saltwithout the pocket above referred to.

- During the electrolysis the solution not only reaches the cathode through the dia- -phra gm, but is also forced to run over a dam ,5 (Fig. 2) in order to wet the cathode from below. Instead of using a dam, a batlie 120 plate 14: (Fig. 3)Imay be provided within bell 11 having 1ts opening near the diaphragm. The pocket, thus formed by this plate, communicates with the trough 10 through 'an' outlet 19 provided at a' suitable '25 height. By this arrangementshownin the two modificationsthe irregularities of supply 'of solution or of the permeability of the diaphragm are equalized on 'one hand, on the other hand, this .heing the most essential 5 point-,this. arrangement has the following particulatgfldvahtage's During the passing of OH 'iOns-t'o-the anodeerowing to insuflicient actioriof'the diaphr gm, soda lye is apt to reach the lower layer 0 the liquid, which 35, in the further course of electrolysis forms with thechlorin, hypochlorite, which latter would cause disturbances in the process and -g'lecrease the-output. By compelling the solu- .tion oontainedin the bell to constantly flow 4 0 -over the dam any trace of soda lye, which in y have diffused into the bell, is washed out immediately since according to the ar- 1 I'flllgBIllGIItNlBSCI'ibed above, just the lower- .mo'st layers next to the diaphragm are compelled to flow over the dam.

As, mentioned already the liquid level is 'kept-inthe trough preferably high .enough to 'wet the "cathode net, which however is not absolutely necessary, as the liquid level may also. be rather below the level of the cathode,

because owing to the filt-rating of the solution through the diaphragm and owing to the liquid fio wing'over the dam the cathode net is permanently. wetted with liquid. (On account of clearness the space between dam 5 p and bell 11 is shown in'Fig. 2 much wider in proportion than it is in the practical apparatuswhere this space is chosen as narrow as. possiblain order to avoid diffusion.)

.6'0 The apparatus. has been subjected to sev- 'eral uninterrupted electrolysis tests, each lasting six weeks and yielding at from four "-10 five volt tension during the'time of the electrolysis an average output of twelve per 6 cent. lye, being equal to from ninety to ninetyelectric circuit.

vbestos cloth is then placed-the asbestos powder mixture. For the purpose of renewfive per cent, (rarely eighty-five to ninety per cent.) of the theoretical output, while at the same time substantially chemically pure chlorin of ninety-nine per cent. .was

obtained.

4 to 4.5 volts and a temperature of 60 C.,'

about 600'amperes.. a I

In smaller apparatus (up tic-100 amperes capacity) it is more advantageous to fix the asbestos cloth to the bell. The whole bell, 30 together with the diaphragm may then be placed upon a corrugated wire net of sufii-' cient strength corresponding in form with the bottom of the outer trough andresting thereon. The trough .10 may be made to advantage of sheet iron, which serves in this instance atthe same time as a part of the For larger apparatus (consuming more than 100 amperes) the structure above. referred to is not suited. 'In apparatus of that size it is more'practical to have the cathode net fixed to the bell.

In order to facilitate the exchanging of -the diaphragm without renewing the bell,

the cover 21 of the latter and the bafiie plate 14 are made easily removable (Fig. 3). The asbestos cloth is not fixed to the bell but is held in place by means of a frame'lS of stone or other suitable material, running on the inside 'of the trough and held in place by means of wedges. For tightening the frame against leakage if necessary a non soluble powder may be used. Upon the asing the diaphragm it is only necessary to remove the bell cover, the baffle plate and t-he'fra-me, whereafter the diaphragm may be exchanged in a few minutes. In Fig. 3 is shown an apparatus by means of which it is also poss ble to collect the hydrogen separately. For this purpose a tight fitting frame 15 running oh the outside of hell 11 is resting u'pon a'rim 20 provided on the bell and upon the upper rim of; trough 10 which is suitably shaped for this purpose as shown in Fig. 3. The'channel thus formed by the bell, the trough edge and frame 15 may be filled with a liquid 16 of suitable kind to further tighten the frame against leakage of gas; i

The pressure at which the hydrogen is discharged through the opening 17 may be easily regulated by regulating the liquid level at thedischarge opening 13.

The hydrogen may be either utilized as such or may be used'with the chlorin generated during the electrolysis for directly producing chemically pure hyro-chloric acid 130 means of a blow pipe similar to the 6;

-hydrogen blow pipe.

In order to free the hydrogen of the atom} iz'e'dts oda lye carried'alongbyisame while rising; it must of coursepass through a long tube or over a body of large surface before it can be used in connection with ehlorinf l asabove mentioned."

While I have describ my novel process is carried out, I do/not claim the particular novel features of these Vvhatl claim is:

electrolysis of alkali chlorids, comprising the compelling a part of the cathode product to form a thin'layer in the" electrolyte and formed.

- 2;.The hereinbefore described process for electrolysis of alkali chloride, comprising.

the compelling a part of the cathode product to form a thin layer in the electrolyte and the constant removal of said layer as it isv formed through an opening of suitable size 'dis osed atthe height at'which said layer,

is ormed; 3. The hereinbefore described process for electrolysis of alkali chlorids, comprising -the compelling a part of the cathode product to form a thin layer in the electrolytefand' the constant removal of said layer as it is formed through an openin of suitable size disposed at the height at W ich said layer is g d and shown-various forms-of the'apparatus means of which- 1. The hereinbefore described process for i formed by constantly adding'fres'h solution to the electrolyte; I

i 1 4. The hereinbefore describeo process for electrolysis of alkali chlorids, comprising the compelling'a. part of the cathode product to form a1 thin alkali-containing layer of higher specific gravity immediately above a diaphragm, and the constant removal of only said layer. from above the diaphragm through an opening of suitable size disposed at the height at which said layer is formed by constantly adding fresh solution to the electrolyte.

5'. The hereinbefore described process for electrolysis offalkali chlorids, comprising thecompelling a part of the cathode product to form a thin alkali-containing layer of higher specific gravity immediately above a diaphra 'm, and the constant removal of the constant removal of said layer as it is only said daye'r from above the diaphragm through an opening of suitable size disposed at the height at "which said layer is formed and also comprising the removal of said layer by percolation through said diaphragm by constantly addin collecting underneath the cathode being prevented by preventing the electrolyte from rising above the level of the cathode.

In )Vltl'lGSS whereof, I hereunto subscribe my name this 10th day of January A. D.

JEAN BILLITZER, .,Witnesses WOLDEMAR HAUP'r,

HENRY HASPER.

fresh solution to the electrolyte, th'e're-di usion of the electrolyte 

